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GLOSSARY OF AQUATIC ECOLOGICAL TERMS 



Environmental Protection Agency 



February 1972 



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GLOSSARY OF AQUATIC ECOLOGICAL TERMS 



compiled by 

John E. Matthews 
Aquatic Biologist 



Reproduced by 

NATIONAL TECHNICAL 
INFORMATION SERVICE 

US Department of Commerce 
Sptinofield, VA. 22)51 



Manpower Development Branch 
Air and Water Programs Division 

Region VI 

Environmental Protection Agency 

Ada, Oklahoma 74820 

September 1969 

Revised 

February 1972 



(I 



PREFACE 



This Glossary is intended to provide familiarity and under- 
standing of technical terminology specific to the discipline of 
aquatic ecology and will serve as a convenient reference for all 
professionally trained persons concerned with water pollution control. 

Definitions have been carefully reviewed to assure accord with 
current professional usuage. Appreciation is tendered to biologists 
of the following Environmental Protection Agency activities for 
this service: Robert S. Kerr Water Research Center, Ada, Oklahoma; 
National Field Investigations Center, National Training Center, 
Analytical Quality Control Laboratory, Cincinnati, Ohio; National 
Water Quality Laboratory, Duluth, Minnesota; National Marine Water 
Quality Laboratory, West Kingston, Rhode Island. 

Terms specifically identifying or describing organisms have 
generally been excluded from this work. For this information the 
reader is referred to the selected references presented in the 
appendix. Glossaries of terminology related to other disciplines 
concerned with water pollution control are also listed in the 
appendix. 

Terms underscored in a definition are separately defined 
in this Glossary. Where appropriate, closely associated or 

related terms are cited parenthetically, (See ), following 

the definition. Specific synonyms are noted, in parentheses, 
with the listed word. 



John E, Matthews 



A-/ 



ABYSSAL ZONE 



All of a sea, or a very deep lake below the 
bathyal zone . The primary energy source for 
this region lies far above in the euphotic zone ; 
density of life depends on the amount of organic 
material that settles from the euphotic zone . 
(See Hadal Zone) 



ACCLIMATION 



Physiological and behavioral adjustments of an 
organism in response to a change in environment, 
(See Adaptation) 



ACCLIMATIZATION 



Acclimation of a particular species over 
several generations in response to marked 
environmental changes. 



ACUTE TOXICITY 



ACTINOMYCETES 



Any toxic effect that is produced within a 
short period of time, usually 24-96 hours. 
Although the effect most frequently considered 
is mortality, the end result of acute toxicity 
is not necessarily death. Any harmful biological 
effect may be the result. (See Chronic Toxicity , 
Direct Toxicity) 

Filamentous microorganisms intermediate between 
the fungi and bacteria, although more closely 
related to the bacteria. These organisms are 
widely distributed in soils and are often 
conspicuous in lake and river muds. They are 
often associated with taste and odor problems 
in water supplies. 



A-2 
ADAPTATION 



Change in the structure, form or habits of an 
organism to better fit changed or existing 
environmental conditions. (See Acclimation) 



AEROBIC 



Refers to life or processes occurring only in 
the presence of free oxygen; refers to a 
condition characterized by an excess of free 
oxygen in the aquatic environment. (See 
Anaerobic) 



ALGAE (Alga) 



Simple plants, many microscopic, containing 
chlorophyll . Algae form the base of the 
food chain in aquatic environments. Some 
species may create a nuisance when environmental 
conditions are suitable for prolific growth. 



ALLOCHTHONOUS 



Pertaining to those substances, materials or 
organisms in a waterway which originate outside 
and are brought into the waterway. (See 
Autochthonous ^ 



ALLUVIAL 



Pertaining to material that is transported 
and deposited by running water. 



ALLUVIAL FAN 



(Delta) 



ANABOLISM 



Synthesis or manufacture of organic compounds 
within an organism. (See Metabolism) 



A- 3 
ANADROMOUS 



Pertaining to fishes that spend most of their 
life in salt water but enter freshwater to 
spawn ; e.g., salmon, shad, striped bass, etc. 
(See Catadromous) 



ANAEROBIC 



Refers to life or processes occurring in the 
absence of free oxygen; refers to conditions 
characterized by the absence of free oxygen. 
(See Aerobic) 



ANTAGONISM 



Reduction of the effect of one substance 
because of the introduction or presence of 
another substance; e.g., one substance may 
hinder, or counteract, the toxic influence 
of another. (See Synergism ) 



APHOTIC ZONE 



That portion of a body of water to which 
light does not penetrate with sufficient 
intensity to have any biological significance. 
(See Euphotic Zone ) 



AQUATIC VASCULAR 
PLANTS 



( Higher Aquatic Plants ) 



ARTIFICIAL 
SUBSTRATE 



A device placed in the water (for a specified 
period of time ) that provides living spaces 
for a multiplicity of organisms; e.g., glass 
slides, concrete blocks, multiplate samplers, 
rock baskets, etc. The primary purpose of 
artificial substrates is to allow the investi- 
gator to collect organisms in areas where the 
physical habitat is limiting or cannot be 
adequately sampled using conventional methods. 



A-4 



ASSIMILATION 



1. Removal of dissolved or suspended materials 
from a water mass by biological, chemical 
and physical processes; 

2. Conversion or incorporation of absorbed 
nutrients into body substances. (See 
Synthesis ) 



ASSOCIATION 



All organisms occupying a given habitat . 



ATOLL 



Large, thick, coral mass encircling a lagoon 
in tropical oceans; cometimes portions of the 
reef become built up with sand, silt, soil and 
vegetation to become an island. (See Barrier 
Reef , Fringing Reef ) 



AUFWUCHS 



( Periphyton ) 



AUTOCHTHONOUS 



Pertaining to those substances, materials, 
or organisms originating within a particular 
waterway and remaining in that waterway. 
(See Allochthonous) 



AUTOTROPHIC 
(Holophytic) 



Self nourishing; denoting those organisms that 
do not require an external source of organic 
material but can utilize light energy and 
manufacture their own food from inorganic 
materials; e.g., green plants, pigmented 
flagellates. (See Heterotrophic) 



B-A 



BACTERIA 



Microscopic, single-celled or noncellular 
plants, usually saprophytic or parasitic. 



BARRIER BEACH 



A ridge of deposits separated from the 
mainland by an interval of water. 



BARRIER REEF 



Large, thick, coral mass more or less 
surrounding an island or paralleling the 
mainland shore in tropical areas; separated 
from the land mass by a lagoon. (See Atoll , 
Fringing Reef ) 



BATHYAL ZONE 



That region of the sea that extends from the 
euphotic zone to the bottom of the continental 
slope . Density of life in this zone depends 
on organic material settling from the euphotic 
zone and is generally inversely proportional 
to the depth. 



BEACH 



The zone of demarcation between land and water 
of lakes, seas, etc.; covered by sand, gravel 
or larger rock fragments. 



BENTHIC REGION 



The bottom of a waterway; the substratum that 
supports the benthos . 



B-2 
BENTHOS 



Organisms growing on or associated principally 
with the bottom of waterways. These include: 

(1) sessile animals such as sponges, barnacles, 
mussels, oysters, worms, and attached algae; 

(2) creeping forms such as snails, worms and 
insects; (3) burrowing forms, which include 
clams, worms, and some insects; and (4) fish 
whose habits are more closely associated with 
the benthic region than other zones; e.g., 
flounders. 



BIOASSAY 



A determination of the biological effect of 
some substance, factor or condition employing 
living organisms or cells as the indicator. 



BIOCOENOSIS 



The plants and animals comprising a community . 



BIOLOGICAL 
CONTROL 



1. Use of natural predators , parasites or 
viruses to reduce or eliminate pest 
organisms; e.g., use of gambusia to 
feed on mosquito larvae; 

2. Control of organisms by interference 
with their physiological processes; 
e.g., sterilization of male flies. 



BIOLOGICAL 
MAGNIFICATION 



The ability of certain organisms to remove 
from the environment and store in their tissues 
substances present at nontoxic levels in the 
surrounding water. The concentration of these 
substances becomes greater each higher step 
in the food chain. (See Enrichment Factor) 



B-3 
BIOMASS 



The total amount of living material in a 
given habitat or area; or, an expression 
dealing with the total weight of a given 
population of organisms. 



BIOMONITORING 



1. Continuous surveillance of an effluent 
(or dilution thereof) by using living 
organisms to test its suitability for 
discharge into a receiving water. 

2. Use of living organisms to test the 
quality of a receiving water downstream 
from a waste discharge. (See Bioassay ) 



BIOSTIMULATION 



A general term used to describe the complex 
set of factors involved in the growth of algae 
(and other organisms) in a receiving water 
due to the addition of nutrients. 



BIOTA 



All life of a region. 



BIOTIC FACTORS 
(Biological 
Factors) 



In ecology , those environmental factors which 
are the result of living organisms and their 
activities; distinct from physical and chemical 
factors; e.g., competition , predation, etc. 
(See Ecological Factor) 



BIOTIC POTENTIAL 



The inherent capability of an animal to multiply 
in an unrestricted environment . (See 
Environmental Resistance) 



B-4 
BIOTOPE 



(Habitat) 



BLOODWORMS 



Midge fly larvae . Many of the species have 
hemoglobin in the blood causing a red color 
and are often associated with rich organic 
deposits. Also, the common name for certain 
of the marine segmented worms (class Polychaeta) . 
(See Sludgeworms ) 



BLOOM 



A readily visible concentrated growth or 
aggregation of minute organisms, usually 
algae , in bodies of water. 



BRACKISH WATERS 



Those areas where there is a mixture of fresh 
and salt water; or, the salt content is 
greater than fresh water but less than sea 
water; or, the salt content is greater than 
in sea water. 



o/ 



CARNIVOROUS 



Pertaining to animals that feed on other 
animals. (See Herbivorous) 



CARRYING CAPACITY 



The maximum quantity of organisms that any 
particular habitat can support over an 
extended period. 



CATABOLISM 



The breakdown of organic compounds within an 
organism. (See Metabolism) 



CATADROMOUS 



Pertaining to fish that spend most of their 
life in freshwaters; but migrate to the sea 
to spawn ; e.g., american eel. (See Anadromous) 



CATASTROPHIC 
DRIFT 



Massive drift of bottom organisms under 
conditions of stress such as floods or toxicity . 
(See Drift Organisms . Incidental Drift , 
Periodic Drift) 



CHEMICAL 
STRATIFICATION 



A layering of water in a lake because of 
density differences owing to the varying or 
differential concentrations of dissolved 
substances with depth. (See Stratification) 



CHLOROPHYLL 



Green photosynthetic pigment present in many 
plant and some bacterial cells. There are seven 
known types of chlorophyll; their presence 
and abundance vary from one group of photosyn- 
thetic organisms to another. 



C-2 



CHRONIC TOXICITY 



Toxicity , marked by a long duration, that 
produces an adverse effect on organisms. The 
end result of chronic toxicity can be death 
although the usual effects are sublethal; e.g., 
inhibits reproduction, reduces growth, etc. 
These effects are reflected by changes in the 
productivity and population structure of the 
community . (See Acute Toxicity) 



CLASSIFICATION 



The placing of organisms into groups (or 
categories) according to established scientific 
requirements. (See Taxonomy) 



CLEAN WATER 
ASSOCIATION 



An association of organisms found in any 
natural, unpolluted environment . These 
associations are characterized by the presence 
of species that are sensitive to environmental 
changes caused by Introduction of pollutants. 
In many cases the presence of a wide variety 
of species with relatively few individuals 
representing any one of them is also a 
characteristic. (See Sensitive Organisms , 
Tolerant Association) 



COASTAL PLAIN 



A plain between the sea and higher land, 
usually at a low elevation. 



COASTAL WATERS 



Those waters surrounding the continent which 
exert a measurable influence on uses of the 
land and on its ecology . The Great Lakes 
and the waters to the edge of the continental 
shelf. 



C-3 

COASTAL ZONE 



Coastal waters and adjacent lands which exert 
a measurable influence on the uses of the sea 
and its ecology. The zone extends onshore to 
the upper reaches of the tidal zone and adjacent 
shore areas. (See Estuary) 



COLD-BLOODED 
ANIMALS 



Animals that lack an internal temperature 
regulating mechanism to offset external 
temperature changes. Their body temperature 
fluctuates to a large degree with that of 
their environment. Examples are fish and 
aquatic invertebrates . 



COLONY 



A distinguishable localized population within 
a species . 



COMMUNITY 



An aggregation of organisms within a specified 
area; all forms of life inhabiting a common 
environment. 



COMPENSATION 
LEVEL 



The depth of a waterway at which there is a 
balance between photosynthesis and respiration . 



COMPETITION 



The effort of two or more individuals or 
species of a community to utilize some of the 
same environmental resources. 



COMPETITION No two species can occupy the same niche at 

EXCLUSION PRINCIPLE 
(Gause's Rule) 



the same time. 



C-4 
CONSUMERS 



Heterotrophic organisms, chiefly animals, 
that ingest other organisms or particle 
organic matter. Often divided into primary 
consumers (Herbivores ) , secondary consumers 
( Carnivores which eat primary consumers), etc. 
(See Heterotrophic , Trophic Level ) 



CONTINENTAL SHELF 



The shallow, gently sloping portion of the 
seabottom bordering a continent, down to a 
depth of about 200 meters. 



CONTINENTAL SLOPE 



The steeply sloping portion of the seabottom 
extending seaward from the continental shelf . 



CORAL 



A marine member of the phylum Coelenterata 
which secretes a hard exoskeleton, chiefly of 
calcium carbonate. 



CORAL REEF 



Large coral mass associated with coastal areas 
in the tropics (See Barrier Reef , Fringing 
Reef, Atoll) 



CRITERIA 



( Water Quality Criteria ) 



CRITICAL LEVEL 



(Threshold) 



CRITICAL RANGE 



In bioassays , the range of magnitude of any 
factor between the maximum level or concentration 
at which no organisms die to the minimum level 
or concentration at which all organisms die 
under a given set of conditions in a given 
period of time. 



C-5 

CULTURAL Acceleration by man of the natural process of 

EUTROPHICATION enrichment (aging) of bodies of water. 

CULTURE Cultivation of organisms in a medium containing 

necessary nutrients . 



D-/ 



DECOMPOSERS 



( Reducers) 



DELTA 
(Alluvial Fan) 



A fan-shaped deposition of silt, sand, gravel 
or other fine materials from a stream. These 
occur when the hydraulic gradient lessens 
abruptly, as in the discharge of a stream 
into a lake, or a river into an ocean. 
(See Alluvial) 



DENSITY 
(Population 
Species) 



The number of individuals in relation to the 
space in which they occur; refers to the 
closeness of individuals to one another 
at a given time. 



DENSITY 
STRATIFICATION 



(Stratification) 



DEPOSITING 
SUBSTRATES 



Bottom areas where solids are being actively 
deposited because of slackening movement of 
the transporting agent. These often occur 
in the vicinity of effluent discharges. 
(See Sludge Deposits ) 



DETRITUS 



Fragments of detached or broken down material. 



DIRECT TOXICITY 



Toxicity that has an effect on organisms 
themselves instead of having an effect by 
alteration of their habitat or interference 
with their food supply. (See Acute Toxicity , 
Chronic Toxicity , Indirect Toxicity) 



D-2 
DIURNAL 



1. Refers to an event, process, or specific 
change that occurs every day; usually 
associated with changes from day to night. 

2. Pertaining to those organisms that are 
active during day time. (See Nocturnal ) 



DIVERSITY 



Pertaining to the variety of species within a 
given association of organisms. Areas of high 
diversity are characterized by a great variety 
of species; usually relatively few individuals 
represent any one species . Areas with low 
diversity are characterized by a few species; 
often relatively large numbers of individuals 
represent each species. 



DOMINANT SPECIES 



Species of a community which by their activity, 
behavior, or number, have considerable 
influence or control upon the conditions of 
existence of associated species; species 
which "controls" its habitat and food web . 
(See Predominant) 



DRIFT ORGANISMS 



Benthic organisms temporarily suspended in the 
water and carried downstream by the current. 
(See Incidental Drift , Periodic Drift , 
Catastrophic Drift ) 



l>-3 

DYSTROPHIC LAKES Shallow lakes with hrown water, high humic 

material and organic matter content, low 
nutrient availability, poor bottom fauna, 
and high oxygen demand; oxygen is continually 
depleted and pH is usually low. In lake aging 
the "age" between a eutrophic lake and a swamp. 



EBB TIDE 



E-/ 



That period of tide between a high water and 
the succeeding low water; falling tide. 
(See Flood Tide) 



EC 50 



Concentration of a substance producing 50% 
decrease in shell growth. 



ECOLOGICAL FACTOR 



Any part or condition of the environment that 
influences the life of one or more organisms. 
(See Biotic Factor) 



ECOLOGICAL NICHE 



The role of an organism in an ecosystem , 
its activities and relationships to the 
living and nonliving environment; food 
and nutrition relationships are of primary 
importance. (See Habitat Niche) 



ECOLOGY 



Interrelationships between organisms and their 
environment . 



ECOSYSTEM 



A community , including all the component 
organisms, together with the environment , 
forming an interacting system. 



ECOTYPE 
(Habitat Form) 



A locally adapted population of a species which 
has a distinctive limit of tolerance to envi- 
ronmental factors. (Individuals of the same 
species may appear different in various 
habitats) . 



E-2 



EMERSED (Emergent) 
AQUATIC PLANTS 



Plants that are rooted at the bottom of a body 
of water, but project above the surface; e.g., 
cattails, bulrushes, etc. (See Floating 
Aquatic Plants , Submersed Aquatic Plants ) 



ENRICHMENT 



An increase in the quantity of nutrients 
available to aquatic organisms for their 
growth. (See Eutrophication ) 



ENRICHMENT FACTOR 



Number of times a substance is concentrated 
in the tissue of an organism over the 
concentration in its environment. (See 
Biological Magnification ) 



ENVIRONMENT 



All external influences and conditions affecting 
the life and development of an organism or 
community . 



ENVIRONMENTAL 
RESISTANCE 



Restriction imposed on the numerical increase 
of a popula tion by environmental factors. 
(See Biotic Potential) 



EPILIMNION 



The water mass extending from the surface to 
the thermocline in a stratified body of water; 
the epilimnion is less dense than the lower 
waters and is wind-circulated and essentially 
homothermous . (See Hypolimnion ) 



EQUILIBRIUM 



The condition in which a population or community 
is maintained with only minor fluctuations in 
composition over an extended period of time. 



E-3 
ESTUARY 



That portion of a coastal stream influenced by 
the tide of the body of water into which it 
flows; a bay, at the mouth of a river, where 
the tide meets the river current; an area 
where fresh and marine waters mix. (See 
Positive Estuary , Inverse Estuary , Neutral 
Estuary , Coastal Zone ) 



EULITTORAL ZONE 



(Tidal Zone) 



EUPHOTIC ZONE 



The lighted region of a body of water that 
extends vertically from the water surface 
to the depth at which photosynthesis fails 
to occur because of insufficient light 
penetration. 



EURY- 



Prefix meaning wide; e.g., euryhaline refers 
to a wide range of salienty tolerance; 
eurythermal refers to a wide range of 
temperature tolerance. (See Steno- ) 



EUTROPHIC LAKES 



Lakes which are rich in nutrients and organic 
materials, therefore, highly productive. These 
lakes are often shallow and seasonally deficient 
of oxygen in the hypolimnion . (See Oligotrophic 
Lakes) 



E-4 

EUTROPHI CATION The natural process of the maturing (aging) of 

a lake; the process of enrichment with nutrients , 
especially nitrogen and phosphorus, leading to 
increased production of organic matter. (See 
Cultural Eutrophication , Oligotrophia: Lakes , 
Eutrophic Lakes ) 



F-/ 



FALCULTATIVE 



Refers to the capability of an organism to 
live under varying conditions; e.g., a 
f alcultative anaerobe is an organism that 
although usually living in the presence of 
free oxygen can live in the absence of free 
oxygen. (See Obligate) 



FALL OVERTURN 



A physical phenomenon that may take place in 
a body of water during early autumn. The 
sequence of events leading to fall overturn 
include: (1) cooling of surface waters, 

(2) density change in surface waters producing 
convection currents from top to bottom, 

(3) circulation of the total water volume by 
wind action, and (4) vertical temperature 
equality. The overturn results in a uniformity 
of the physical and chemical properties of the 
entire water mass. (See Spring Overturn) 



FATHOM 



A unit of measurement equal to 6 feet (1.83 
meters) . 



FAUNA 



Animal life . 



FIRTH 



A narrow arm of the sea; also the opening of 
a river into the sea. (See Estuary) 



FJORD 
(Fiord) 



A narrow arm of the sea between highlands . 
(See Firth . Estuary) 



F-2 



FLOATING AQUATIC 
PLANTS 



Rooted plants that wholly or In part float 
on the surface of the water; e.g., water lilies, 
water hyacinth and duckweek. (See Emersed 
Aquatic Plants , Submersed Aquatic Plants) 



FLOOD TIDE 



That period of tide between low water and the 
succeeding high water; a rising tide. (See 
Ebb Tide) 



FLORA 



Plant life. 



FLUVIAL 



Of or pertaining to rivers; growing or living 
in streams; produced by river action, as a 
fluvial plain. 



FOOD CHAIN 



Dependence of a series of organisms, one upon 
the other, for food. The chain begins with 
plants and ends with the largest carnivores; 
e.g. , phytoplankton ■»■ zooplankton ■* forage 
fish -*■ game fish. 



FOOD CYCLE 
(Food Web) 



All the interconnecting food chains In a 
community . 



FORAGE FISH 



Fish, usually smaller prolific species, that 
are important as food for predatory species. 



FREE-SWIMMING 
(Motile) 



Actively moving about in water or capable of 
moving about in water. (See Sessile) 



F-3 

FRINGING REEF Large coral mass at the edge of any land mass 

In tropical seas; It begins at the water's 
edge and may extend out to a quarter mile. 
(See Barrier Reef, Atoll) 



G-/ 



GAME FISH 
(Sport Fish) 



Those species of fish considered to possess 
sporting qualities on fishing tackle; e.g., 
salmon, trout, black bass, striped bass, etc. 
Game fish are usually considered to be more 
sensitive to environmental changes than 
rough fish . 



CAUSE'S RULE 



( Competition-Exclusion Principle) 



H- / 



HABITAT 
(Biotope) 



A specific type of place that is occupied by 
an organism , a population , or a community . 



HABITAT FORM 



( Ecotype ) 



HABITAT NICHE 



The specific part or smallest unit of a habitat 
occupied by an organism. (See Ecological Niche ) 



HADAL ZONE 



Pertaining to that part of the ocean at depths 
exceeding 6000 meters, including both water 
and floor or bottom. (See Abyssal Zone) 



HERBICIDE 



A chemical substance used for killing plants, 
especially weeds. 



HERBIVORE 



An organism that feeds on plant material, 
(See Carnivore) 



HETEROGENEOUS 



Consisting of dissimilar elements or constituents, 
(See Homogeneous ) 



HETEROTROPHIC 
(Holozoic) 



Pertaining to organisms that are dependent 

on organic material for food. (See Autotrophic ) 



HIGHER AQUATIC 
PLANTS 
(Pond Weeds, 
Aquatic Vascular 
Plants) 



Those plants composed of complex and differentiated 
tissues whose seeds germinate in the water phase or 
substrate of a body of water and which must spend 
part of their life cycle in water. This grouping 
includes plants which grow completely submersed 
as well as a variety of emersed and floating leaf 
types. (See Macrophyte ) 



H-2 
HOLOPHYTIC 

HOLOZOIC 

HOMOGENEOUS 

HOMOTHERMOUS 

HYPOLIMNION 



( Autotrophic ) 

( Heterotrophic ) 

Of uniform composition throughout. 

Having the same temperature throughout. 

The region of a body of water that extends 
from the thermocline to the bottom and is 
essentially removed from major surface 
influences. (See Epilimnion ) 



IDENTIFICATION 



I- / 

The use of a taxonomic key or the equivalent 

to determine the scientific name of an organism. 



INCIDENTAL DRIFT 



The casual, random drift of organisms. 
(See Drift Organisms , Catastrophic Drift , 
Periodic Drift) 



INCIPIENT LETHAL 
LEVEL (ILL) 



That concentration of an environmental identity 
beyond which an organism could no longer 
survive for an indefinite period of time. 



INDICATOR ORGANISMS 



A species , whose presence or absence may be 
characteristic of environmental conditions in 
a particular area or habitat ; however, species 
composition and relative abundance of individual 
components of the population or community are 
usually considered to be a more realiable 
index of water quality. 



INDIGENOUS 



Refers to an organism that is native, not 
introduced in an area. 



INDIRECT TOXICITY 



INLET 



Toxicity that affects organisms by interfering 
with their food supply or modifying their 
habitat instead of directly acting on the 
organisms themselves. (See Direct Toxicity ) 

A short, narrow waterway connecting a bay, 
lagoon , or similar body of water with a large 
parent body of water; an arm of the sea, or 
other body of water, that is long compared to 
its width, and that may extend a considerable 
distance inland. 



1-2 
INSTAR 



A stage in the life cycle of an insect or other 
arthropod between two successive molts . 



INTERACTION 



Mutual or reciprocal action or influence between 
organisms, between organisms and environment , 
or between environmental factors. 



INTERSPECIFIC 



Refers to relations or conditions between 
species . (See Intraspecific ) 



INTERTIDAL ZONE 



(Tidal Zone) 



INTOLERANT 
ORGANISMS 



( Sensitive Organisms ) 



INTRASPECIFIC 



Refers to relations or conditions between 
individuals within a species . (See 
Interspecific ) 



INVERSE ESTUARY 



Type of est ary in which evaporation exceeds 
the supply of freshwater; evaporation > 
freshwater inflow + precipitation. (See 
Positive Estuary , Neutral Estuary ) 



INVERTEBRATES 



Animals without an internal skeletal structure; 
e.g., insects, mollusks, crayfish. (See 
Veterbrate) 



LAGOON 



w 

1. A shallow sound, pond, or channel near 
or communicating with a larger body of 
water. 

2. A settling pond for treatment of wastewater. 



LARVA 



The immature form of an animal which is unlike 
its parents. Larva are usually self-feeding 
but must pass through some sort of metamorphosis 
before assuming the characteristics of the 
adult; in insects, the wormlike stage between 
the egg and the pupa . 



LAW OF THE MINIMUM, 
LIEBIG'S 



"The growth and reproduction of an organism 
is dependent on the nutrient substance, such 
as oxygen, carbon dioxide, calcium, etc., that 
is available in minimum quantity." (See 
Limiting Factor ) 



LAW OF TOLERANCE, 
SHELFORD ' S 



"When one environmental factor or condition is 
near the limits of toleration, either minimum 
or maximum, that one factor or condition will 
be the controlling one and will determine 
whether or not a species will be able to 
maintain itself." (See Limiting Factor) 



LENTIC 



Pertaining to standing (nonflowing) waters 
such as lakes, ponds, and swamps. (See Lotic) 



LIFE CYCLE 



The various phases, changes, or stages through 
which an individual passes from the fertilized 
egg to death of the mature organism. (See 
Metamorphosis) 



L-2 



LIMITING FACTOR 



A factor whose absence, or excessive concentration, 
exerts some restraining influence upon a 
population through incompatibility with species 
requirements or tolerance . (See Law of the 
Minimum , Law of Tolerance) 



LIMNETIC ZONE 



The open -water region of a lake, especially in 
areas too deep to support rooted aquatic plants. 
This region supports plankton and fish as the 
principal plants and animals . (See Littoral 
Zone) 



LIMNOLOGY 



The ecology of fresh waters . 



LITTORAL ZONE 



The shallow area that extends from shore to 
the lakeward limit of rooted aquatic plants; 
the shoreward region of a body of water; in 
marine ecology , the tidal zone . (See Limnetic 
Zone) 



LOTIC 



Pertaining to flowing waters such as streams 
and rivers. (See Lentic) 



M-/ 



MACROORGANISMS Those organisms visible to the unaided eye 
(Macroinvertebrates) ^ wh±ch ^ retained on a u. S . standard 

sieve no. 30 (openings of 0.589 mm.). (See 
Microorganisms ) 



MACROPHYTE 



Any plant that can be seen with the naked, 
unaided eye; e.g., aquatic mosses, ferns, 
liverworts, rooted plants, etc. 



MARL 



An earthy, unconsolidated deposit formed in 
freshwater lakes, chiefly of calcium carbonate 
mixed with clay or other impurities in 
varying proportions. 



MARSH 



Periodically wet or continually flooded area 
with the surface not deeply submerged. Covered 
dominantly with emersed aquatic plants ; e.g., 
sedges, cattails, rushes. 



MEDIAN TOLERANCE 
LIMIT (TLm) 



The concentration of tested substance in 
water at which just 50% of the test organisms 
survive for a specified period of exposure. 
(See Tolerance Limit) 



MEROMICTIC LAKES 



Lakes in which dissolved substances create 
a gradient of density differences with depth; 
this prevents complete mixing or circulation 
of water masses. (See Chemical Stratification) 



M-2 



MEROMIXIS 



A condition of permanent stratification of 
water masses in lakes. 



MESOLIMNION 



(Thermocline) 



METABOLISM 



The sum of all chemical processes occurring 
within an organism; includes both synthesis 
(anabolism) and breakdown ( catabolism ) of 
organic compounds. 



METALIMNION 



(Thermocline) 



METAMORPHOSIS 



Abrupt transformation of an animal from one 
distinctive life history stage to another 
in its postembryonic development; e.g., 
larva of an insect to a pupa . (See Life Cycle ) 



MICROORGANISMS Those minute organisms invisible or only barely 

(Microinvertebrates) . .., , ,, . 

visible to the unaided eye. Microorganisms 

pass through a U. S. standard series no. 30 

sieve but are retained on a no. 100 sieve 

(openings of 0.149 mm). (See Macroorganisms) 



MOLT 



To cast or shed periodically the outer body 
covering which permits an increase in size. 
This is especially characteristic of inverte- 
brates. (See Ins tar) 



MOTILE 



( Free-Swimming ) 



NANOPLANKTON 



N-/ 



Very minute p lankton not retained in a plankton 
net equipped with no. 25 silk bolting cloth 
(mesh, 0.03 to 0.04 mm.). 



NATIVE SPECIES 



A species that is part of an area's original 
biota. 



NATURAL SELECTION 



Processes occurring in nature which result in 
survival of the fittest and elimination of 
individuals less well adapted to their 
environment. 



NAUPLIUS 



Free-swimming microscopic larval stage 
characteristic of many crustaceans, barnacles, 
etc. 



NEAP TIDES 



Exceptionally low tides which occur twice each 
month when the earth, sun and moon are at 
right angles to each other; these usually 
occur during the moon's first and third 
quarters. (See Spring Tides ) 



NEKTON 



Macroscopic organisms swimming actively in 
water; e.g., fish. (See Plankton ) 



NERITIC ZONE 



Relatively shallow water zone which extends 
from the high-tide mark to the edge of the 
continental shelf. 



NET PLANKTON 



Plankton retained in a plankton net equipped 
with no. 25 silk bolting cloth (mesh, 0.03 
to 0.04 mm. ) . 



N-2 
NEUSTON 



Organisms associated with, or dependent 
upon, the surface film (air-water interface) 
of bodies of water. 



NEUTRAL ESTUARY 



Type of estuary in which neither the freshwater 
inflow nor the evaporation predominates; 
freshwater inflow + precipitation - evaporation. 
(See Positive Estuary , Inverse Estuary) 



NICHE 



(See Ecological Niche. Habitat Niche) 



NOCTURNAL 



Pertaining to those organisms that are active 
at night. (See Diurnal) 



NUISANCE ORGANISMS 
(Pests) 



Those organisms capable of interfering with 
the use or treatment of water. 



NUTRIENTS 



Elements, or compounds, essential as raw 
materials for organism growth and development; 
e.g., carbon, oxygen, nitrogen, phosphorus, 
etc. 



NYMPH 



An immature developmental form characteristic 
of the pre-adult stage in insects that do not 
have a pupal stage; e.g., mayflies and 
stoneflies. (See Larva) 



<W 



OBLIGATE 



Limited to one mode of life or action. (See 
Facultative) 



OCEANIC ZONE 



The region of open ocean beyond the continental 
shelf. 



OLIGOTROPHY LAKES 



OMNIVOROUS 



OPTIMUM LEVEL 



ORGANISM 



OSMOREGULATION 



OVERTURN 
(Turnover) 



Deep lakes which have a low supply of nutrients, 
thus they support very little organic production . 
Dissolved oxygen is present at or near saturation 
throughout the lake during all seasons of the 
year. (See Eutrophic Lakes) 

Feeding on both plant and animal tissue. (See 
Herbivorous. Carnivorous) 

The most suitable degree of an environmental 
factor for the full development of the organism 
concerned. (See Tolerance Range) 

Any living individual. 

The adjustment in the osmotic concentration of 
solutes in body fluids in organisms to 
environmental conditions; e.g., when salmon 
migrate from salt to freshwater. 

The period of mixing, by top to bottom circulation, 
of previously stratified water masses . This 
phenomenon may occur in spring and/or fall; the 
result is a uniformity of physical and chemical 
properties of the water at all depths. (See 
Thermal Stratification , Chemical Stratification , 
Spring Overturn , Fall Overturn) 



0-2 

OXYGEN DEBT 



A temporary phenomenon that occurs in an 
organism when available oxygen is inadequate 
to supply the respiratory demand. During 
such a period the metabolic processes result 
in the accumulation of breakdown products that 
are not oxidized until sufficient oxygen 
becomes available. 



OXYGEN DEFICIT 



The difference between observed oxygen 
concentration and the amount that would 
theoretically be present at 100% saturation 
for existing conditions of temperature and 
pressure. 



PARASITE 



m 

An organism that lives on or in a host organism 
during all or part of its existence. Nourishment 
is obtained at the expense of the host. 



PATHOGEN 
PELAGIC ZONE 



An organism or virus that causes a disease. 

The open sea, away from the shore. Comparable 
with the limnetic zone of lakes . 



PERIODIC DRIFT 



Drift of bottom organisms at regular or 
predictable intervals such as diurnal , 
seasonal, etc. (See Drift Organisms . 
Catastrophic Drift . Incidental Drift) 



PERIPHYTON 
(Aufwuchs) 



Attached microscopic organisms growing on 
the bottom, or other submersed substrates , 
in a waterway. 



PESTICIDE 



Any chemical preparation used to kill pests . 
Includes insecticides, herbicides, fungicides, 
etc. 



PESTS 



(Nuisance Organisms) 



PHOTOSYNTHESIS 



The metabolic process by which simple sugars 
are manufactured from carbon dioxide and 
water by plant cells using light as an 
energy source. (See Chlorophyll) 



PHOTIC ZONE 



( Euphotic Zone) 



P-2 
PHYTOPLANKTON 



The plants of the plankton . Unattached 
microscopic plants subject to movement by 
wave or current action. (See Zooplankton) 



PLANKTON 



Suspended microorganisms that have relatively 
low powers of locomotion, or that drift in 
the water subject to the action of waves and 
currents. (See Benthos, Periphyton , Nekton) 



POND WEEDS 



(Higher Aquatic Plants) 



POOLS 



Areas of a stream, where the velocity of 
current is reduced. The reduced velocity 
provides a favorable habitat for plankton . 
Silts and other loose materials that settle 
to the bottom of pools are favorable for 
burrowing forms of benthos . (See Riffle) 



POPULATION 



A group of interacting individuals of the 
same species , area , or community . 



POSITIVE ESTUARY 



Coastal indentures in which there is a 
measurable dilution of sea water by land 
drainage; freshwater inflow + precipitation > 
evaporation. (See Inverse Estuary, Neutral 
Estuary) 



POTAMON ZONE 



Stream reach at lower elevations characterized 
by reduced flow, higher temperature, and 
lower dissolved oxygen levels . (See Rithron 
Zone) 



P-3 
PREDATOR 



An animal that kills and consumes other 
animals. (See Prey) 



PREDOMINANT 



Those organisms that are of outstanding 
abundance in a particular community for a 
given period of time. (See Dominant) 



PREY 



An animal that is killed and consumed by 
another animal. (See Predator) 



PRIMARY 
PRODUCTIVITY 



The total quantity of protoplasm produced by 
autotrophic organisms per unit of time in a 
specified habitat . 



PRODUCERS 



Organisms that synthesize organic material 
from inorganic substances; e.g., plants. 
(See Consumers , Reducers) 



PRODUCTION 



The process of producing organic material; the 
quantity produced. 



PRODUCTIVITY 



1. Rate of protoplasm formation or energy 
utilization by one or more organisms ; 
total quantity of organic material 
produced within a given period in a 
specified habitat . 

2. Capacity or ability of an environmental 
unit to produce organic material. (See 
Primary Productivity , Secondary Productivity) 



P-4 

PROFUNDAL ZONE 



The deep, bottom-water area beyond the depth 
of effective light penetration. All of the 
lake floor beneath the hypolimnion . 



PROLIFIC 



Pertaining to organisms that have a high 
reproduction rate and normally produce large 
numbers of young. 



PROTOPLASM 



The living material in cells of plants and 
animals . 



PUPA 



An intermediate, usually quiescent , form 
following the larval stage in insects, and 
maintained until metamorphosis to the 
adult stage. (See Larva) 



Q-/ 

QUALITY A term to describe the composite chemical, 

physical, and biological characteristics of 
a water with respect to its suitability 
for a particular use. 

QUIESCENT Refers to the temporary cessation of development. 

movement or other activity. (See Puoa) 



R-/ 



RAPIDS 



Areas of a stream where velocity of current 
is great enough to keep the bottom clear of 
all loose materials, thus providing a firm 
substrate . The surface of the water is 
disrupted by turbulent currents. This area 
is occupied largely by specialized benthic 
or periphytic organisms that can firmly attach 
or cling to a firm substrate . (See Pools , 
Riffles) 



RED TIDE 



A visible red-to-orange coloration of an 
area of the sea caused by the presence of a 
bloom of certain plankton . These blooms are 
often the cause of major fish kills. 



REDD 



A type of fish spawning area associated with 
flowing water and clean gravel. Fishes that 
utilize this type of spawning area include 
trout, salmon, some minnows, etc. 



REDUCERS 
(Decomposers) 



Those organisms, usually bacteria or fungi, 
that break down complex organic material into 
simpler compounds. (See Producers , Consumers) 



REEF 



A ridge of rocks, sand, soil or coral projecting 
from the bottom to or near the surface of the 
wat er . 



RESPIRATION 



The complex series of chemical and physical 
reactions in all living organisms by which 
the energy and nutrients in foods is made 
available for use. Oxygen is used and carbon 
dioxide released during this process. (See 
Metabolism) 



R-2 
RIFFLES 



A shallow rapids in an open stream where the 
water surface is broken into waves by wholly 
or partly submerged obstructions. Riffles 
usually support a wider variety of bottom 
organisms than other stream sections. (See 
Pools) 



RITHRON ZONE 



Stream reach at higher elevations characterized 
by rapid flow, low temperature, and high 
dissolved oxygen levels. (See Potamon Zone ) 



ROUGH FISH 



Those species of fish considered to be of 
poor fighting quality when taken on tackle; 
e.g., carp, gar, suckers, etc. These fish 
are considered undesirable in most situations, 
Most species in the group are more tolerant 
of widely changing environmental conditions 
than game fish . 



s-/ 



SALT MARSH 



Low area adjacent to the sea that is covered 
with salt tolerant vegetation and regularly 
flooded by high tide; similar inland 
areas near saline springs or lakes , though 
not regularly flooded. 



SAPROBIC 



Living on dead or decaying organic matter. 
(See Scavenger) 



SAPROBICITY 



The sum of all metabolic processes which are 
the direct opposite of primary production ; 
can be measured either by the dynamics of 
metabolism or analysis of community structure. 



SAPROBIENSYSTEM 



European system of classifying organisms 
according to their response to organic 
pollution in slow moving streams. 

1. Alpha-Mesosaprobic Zone - Area of active 
decomposition, partly aerobic , partly 
anaerobic , in a stream heavily polluted 
with organic wastes. 

2. Beta-Mesosaprobic Zone - That reach of a 
stream that is moderately polluted with 
organic wastes. 

3. Oligosaprobic Zone - That reach of a 
stream that is slightly polluted with 
organic wastes and contains the mineralized 
products of self-purification from organic 
pollution, but with none of the organic 
pollution remaining. 



S-2 



4. Polysaproblc Zone - That area of a 

grossly polluted stream which contains 
the complex organic wastes that are 
decomposing primarily by anaerobic 
processes. 



SCAVENGER 



An organism that consumes decomposing organic 
matter. 



SECONDARY 
PRODUCTIVITY 



Total quantity of animal (and other 
heterotrophic ) protoplasm produced per unit 
of time in a specified habitat . (See Primary 
Productivity , Productivity ) 



SEICHE 



Periodic oscillations in the water level of 
a lake or other landlocked body of water due 
to unequal atmospheric pressure, wind, or other 
cause, which sets the surface in motion. These 
oscillations take place when a temporary local 
depression or elevation of the water level occurs. 



SENSITIVE ORGANISMS 
(Intolerant 
Organisms) 



Organisms that exhibit a rapid response to 
environmental changes and are killed, driven 
out of the area, or as a group are substantially 
reduced in numbers when their environment is 
fouled. (See Tolerant Association) 



SESSILE 



Pertaining to those organisms that are 
attached to a substrate and not free to 
move about; e.g., periphyton . (See Free- 
Swimming ) 



S-3 
SESTON 



All material, both organic and inorganic, 
suspended in a waterway. Bioseston is the 
living material; abioseston is the non-living 
portion. 



SLUDGE DEPOSITS 



Accumulations of settled, usually rapidly 
decomposing, organic material in the aquatic 
system. A deposit of solids of wastewater 
origin. 



SLIMES 



Substances of viscous organic nature, usually 
formed from microbiological growth. 



SLUDGEWORMS 



Aquatic segmented worms (class - Oligochaeta) 
that exhibit marked population increases in 
waters polluted with decomposable organic 
wastes. (See Bloodworms) 



SPAWN 



1. In aquatic animals, to produce or deposit 
eggs or sperm. 

2. To produce eggs or young. 

3. Eggs of fishes and higher aquatic 
invertebrates. 



SPECIES 
(Both singular 
and plural) 



An organism or organisms forming a natural 
population, or groups of populations , that 
transmit specific characteristics from 
parent to offspring. Each species is 
reproductively isolated from other populations 
with which they might breed. Hybrids, the 
results of interbreeding, usually exhibit a 
loss of fertility. 



S-4 

SPORT FISH 



(Game Fish) 



SPRING OVERTURN 



A physical phenomenon that may take place 
in a body of water during the early spring. 
The sequence of events leading to spring 
overturn include: (1) melting of ice cover, 
(2) warming of surface waters, (3) density 
changes in surface waters producing convection 
currents from top to bottom, (A) circulation 
of the total water volume by wind action, and 
(5) vertical temperature equality. The 
overturn results in a uniformity of the 
physical and chemical properties of the entire 
water mass. (See Fall Overturn, Overturn) 



SPRING TIDE 



Exceptionally high tide which occurs twice 
per lunar month when there is a new or full 
moon, and the earth, sun, and moon are in a 
straight line. (See Neap Tides ) 



STANDARD 



STANDING CROP 



STENO- 



( Water Quality Standard ) 

The quantity of living organisms present in 
an environment at a selected point in time. 

Prefix denoting a narrow range of tolerance 
of an organism to a specific environmental 
factor; e.g., stenothermal refers to temperature; 
stenohaline refers to salienity; etc. (See Eury-) 



STIMULUS 



An influence that causes a response in an 
organism. (See Taxis ) 



S-5 



STRATIFICATION 
(Density 
Stratification) 



Arrangement of water masses into separate, 
distinct, horizontal layers as a result of 
differences in density; may be caused by 
differences in temperature, dissolved or 
suspended solids. (See Thermal Stratification , 
Chemical Stratification) 



STRESS 



The conditions resulting from any environmental 
change that disturbs the normal functioning of 
an animal to such an extent that its chances 
for survival are reduced. 



SUBLITTORAL ZONE 



The part of the shore from the lowest water 
level to the lower boundary of plant growth; 
transition zone from the littoral to 
profundal bottom. 



SUBMERSED 
(Submerged) 
AQUATIC PLANTS 



Higher aquatic plants that grow, or are 
adapted to grow, beneath the surface of the 
water; e.g., pondweed, coontail, etc. 



SUBSTRATE 



The bottom material of a waterway; the base 

or substance upon which an organism is growing; 

a substance undergoing oxidation. 



SUMMER KILL 



Complete or partial kill of a fish population 
in ponds or lakes during the warm months; 
variously produced by excessively warm water, 
by a depletion of dissolved oxygen, and by 
the release of toxic substances from a decaying 
algal bloom, or by a combination of these 
factors. (See Winter Kill) 



S-6 

SUPRALITTORAL ZONE 
(Supratidal Zone) 



The portion of the seashore adjacent to the 
tidal or spray zone. 



SURFACE AQUATIC 
PLANTS 



( Floating Aquatic Plants) 



SYMBIOSIS 



Two organisms of different species living 
in close association , one or both of which 
may benefit and neither is harmed. Such a 
phenomenon is found among organisms in biological 
treatment processes. 



SYNERGISM 



The joint action of two or more substances is 
greater than the sum of the action of each 
of the individual substances; e.g., action of 
certain combinations of toxicants . The 
improvement in performance achieved because 
two agents are working together. (See 
Antagonism) 



SYNTHESIS 



The production of a substance by the union 
of elements or simpler chemical compounds. 



SYSTEMATICS 



( Taxonomy ) 



T-/ 



TAXIS 



Directed movement by an organism in response to 
a stimulus ; e.g., photo taxis is directed movement 
in response to a light stimulus; thermo taxis is 
directed movement in response to heat or cold 
as a stimulus; etc. 



TAXON (Taxa) 



A "kind" of organism . - Any taxonomic unit or 
category of organisms; e.g., species, genus, 
family, order, etc. 



TAXONOMY 
(Systematics) 



Organism classification with reference to their 
precise relationship in the plant or animal 
kingdom; includes the bases, principles, 
procedures and rules of classification. 



TERRESTRIAL 



Growing, living, or peculair to the land, as 
opposed to the aquatic environment. 



TERRITORY 



The area which an animal defends against 
intruders. 



THERMAL 
STRATIFICATION 



The layering of water masses owing to different 
densities in response to temperature. The 
condition of a body of water in which the 
successive horizontal layers have different 
temperatures , each layer more or less sharply 
differentiated from the adjacent ones, the 
warmest (or the coldest) at the top. (See 
Overturn) 



T-2 



THERMOCLINE 
(Mesolimnion, 
Metalimnion) 



The transition zone between the warm epilimnion 
and cold hypolimnion of stratified bodies of 
water; temperature change equals or exceeds 
1°C for each meter of depth. (See Thermal 
Stratification) 



THRESHOLD 
(Critical Level) 



The maximum or minimum duration or intensity 
of a stimulus that is required to produce a 
response in an organism. 



TIDAL FLAT 



The sea bottom, usually wide, flat, muddy and 
nonproductive, which is exposed at low tide. A 
marshy or muddy area that is covered and 
uncovered by the rise and fall of the tide. 



TIDAL MARSH 



A low, flat marshland that is traversed by 
interlacing channels and tidal sloughs; 
periodically inundated by high tides; vegetation 
consists of rushes, grasses, and other salt 
tolerant plants. 



TIDAL ZONE 
(Eulittoral Zone, 
Intertidal Zone) 



The area of a shore between the limits of 
water level fluctuation; the area between 
the levels of high and low tides . 



TIDE 



The alternate rising and falling of water 
levels, twice in each lunar day, due to 
gravitational attraction of the moon and sun 
in conjunction with the earth's rotational 
force. 



TL* (TL 50 ) 



(Median Tolerance Limit) 



T-3 
TOLERANCE 



Relative capability of an organism to endure 
or adapt to an unfavorable environmental 
factor. 



TOLERANCE LIMIT 
(TL 10...100 ) 



The concentration of a substance which some 
specified portion of an experimental population 
can endure for a specified period of time with 
reference to a specified type of response; e.g., 
TL 100 means tna t all test organisms endured 
the stress for the specified time; TLiq means 
only 10% of the test organisms could tolerate 
the imposed stress for the specified time. 
(See Median Tolerance Limit) 



TOLERANCE RANGE 



TOLERANT 
ASSOCIATION 



The range of one or more environmental 
conditions within which an organism can 
function; range between the highest and 
lowest value of a particular environmental 
factor in which an organism can live. 

An association of organisms capable of 
withstanding adverse conditions within the 
habitat . This association is often characterized 
by a reduction in the number of species (from 
a clean water association ) and, in the case of 
organic pollution, an increase in individuals 
representing certain species. 



TOXICANT 



A substance that through its chemical or 
physical action kills, injures, or impairs 
an organism; any environmental factor which, 
when altered, produces a harmful biological 
effect. (See Pesticide) 



T-4 
TOXICITY 



Quality, state or degree of the harmful effect 
resulting from alteration of an environmental 
factor. 



TRIPTON 



The dead suspended particulate matter in 
aquatic habitats; the nonliving portion of 
the Seston. 



TROPHIC LEVEL 



One of the parts in a nutritive series in an 
ecosystem in which a group of organisms in a 
certain stage in the food chain secures food 
in the same general manner. The first or 
lowest trophic level consists of producers 
(green plants) ; the second level of herbivores ; 
the third level of secondary carnivores . 
Most bacteria and fungi are organisms in the 
reducer (decomposer) trophic level. 



TROPHOGENIC 
REGION 



The area of a body of water where organic 
production from mineral substances takes 
place on the basis of light energy and 
photosynthetic activity. 



TROPHOLYTIC 
REGION 



The deep area of a body of water where organic 
breakdown predominates because of light 
deficiency. 



TURNOVER 



( Overturn) 



u-/ 



UBIQUITOUS 

ORGANISMS 



Organisms that can tolerate a wide range of 
environmental conditions or variation; organisms 
that are so active or numerous as to seem to 
be present or existent in all types of 
environments. (See Tolerant Association. 
Sensitive Organisms ) 



UNICELLULAR 



Refers to an organism that consists of only 
one cell; e.g., blue green algae, protozoa, 
bacteria. These organisms may, however, 
be filamentous or colonial in form. 



V- / 

VERTEBRATES Animals that have an internal skeletal 

system. (See Invertebrate) 



w-/ 



WATER POLLUTION 



Alteration of the aquatic environment in 
such a way as to interfere with a designated 
beneficial use. 



WATER QUALITY 
CRITERIA 



"A scientific requirement on which a decision 
or judgement may be based concerning the 
suitability of water quality to support a 
designated use." (See Water Quality Standard ) 



WATER QUALITY 
STANDARD 



"A plan that is established by governmental 
authority as a program for water pollution 
prevention and abatement." (See Water Quality 
Criteria) 



WINTER KILL 



The death of fishes in a body of water during 
a prolonged period of ice and snow cover; 
caused by oxygen exhaustion due to respiration 
and lack of photosynthesis. (See Summer Kill ) 



z-/ 

ZONE An area characterized by similar flora 

or fauna; a belt or area to which certain 
species are limited. 

ZOOPLANKTON The animals of the plankton . Unattached 

microscopic animals having minimal capability 
for locomotion. 



SELECTED REFERENCES ^ ^ 



Anon. Glossary - Water and Wastewater Control Engineering. 

Prepared by Joint Editorial Board Representing APHA, ASCE, 
AWWA, WPCS. 1969. 

Anon. Report of The Committee on Water Quality Criteria. USDI, 
FWPCA. 1968. 

Anon. Resource Conservation Glossary. Soil Conservation 
Society of America. Ankeny, Iowa. 1970. 

Edmonson, W. T. (Editor). Ward and Whipple's Freshwater Biology. 
Second Edition. John Wiley & Sons, Inc. New York. 1959. 

Geckler, J. R. , K. M. Mackenthun and W. M. Ingram. Glossary of 

Commonly Used Biological and Related Terms in Water and Waste 
Water Control. USDHEW, PHS No. 999-WP-2. 1963. 

Hanson, H. C. Dictionary of Ecology. Philosophical Library. 
New York. 1957. 

Ingram, W. M. , K. M. Mackenthun and A. F. Bartsch. Biological Field 
Investigative Data for Water Pollution Surveys. USDI, FWPCA, 
WP-13. Pages 17-46. 1966. 

Kenneth, J. H. (Editor). A Dictionary of Biological Terms. Eighth 
Edition. D. Van Nostrand Company, Inc. New York. 1963. 

Ludzack, F. J. Glossary of Wastewater and Surface Water Technology. 

Reference Outline Series. USDI, FWPCA, National Training Center, 
Cincinnati. 1968. 

Needham, J. G. and P. R. Needham. A Guide to the Study of Freshwater 
Biology. Fifth Edition. Holden-Day, Inc. San Francisco. 1962. 

Odum, E. P. Fundamentals of Ecology. W. B. Saunders Company. 
Philadelphia. 1959. 

Pennack, R. W. Collegiate Dictionary of Zoology. The Ronald Press 
Co. New York. 1964. 

Pennack, R. W. Fresh-Water Invertebrates of the United States. 
The Ronald Press Co. New York. 1953. 



z-3 

Rechard, P. A. and R. McQuisten. Glossary of Selected Hydrologlc 
Terms. Water Resources Research Institute, University of 
Wyoming, Laramie. Water Resources Series No. 1. 1966 (Revised 
1968) . 

Reid, G. K. Ecology of Inland Waters and Estuaries. Reinhold 
Publishing Corporation. New York. 1961. 

Ruttner, F. Fundamentals of Limnology. University of Toronto Press. 
Third Edition. Toronto, Ontario. 1963. 

Stewart, K. M. and G. A. Rohlich. Eutrophication - A Review. A 
Report to the State Water Quality Control Board, California. 
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